Two questions to be addressed in this application are: how are class II genes controlled in the developing fetus and what happens when class II genes are expressed at different times during gestation? Experiments are designed to 1) determine the molecular mechanism of regulation by examining class II specific transcription factors and promoter occupancy in fetal tissues, 2) identify cytokines that regulate class II expression on fetal tissues, 3) determine the effects of fetal or maternal class II expression during gestation by creating transgenic mice that will carry an inducible global regulator of class II gene expression.